Adjustable spinal implant device and method

ABSTRACT

A spine implant, in particular a stabilization or distraction device, is provided with an adjustable length. The implant has first and second portions for coupling to a first bony portion of a first vertebra and a second bony portion of a second vertebra, respectively, where the second bony portion is located at an oblique angle to the first bony portion. The spinal implant permits movement between the first bony portion and the second bony portion and is adjustable to change an amount of said movement between said first bony portion and said second bony portion after the implant is implanted.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of application Ser. No.11/197,041, filed Aug. 3, 2005 and entitled “Spine Stabilization Deviceand Method,” which claims the benefit of U.S. Provisional ApplicationNo. 60/598,882, filed Aug. 3, 2004 and entitled “Spine Treatment Devicesand Methods,” the disclosure of each of which is hereby incorporated byreference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to devices to treat the spine, including but notlimited to spinal stabilization devices, dynamic stabilizers, spinaldeformity correction devices, devices to treat pain associated with thespine, and other spinal treatment devices.

2. Description of the Related Art

Certain spine conditions, defects, deformities (e.g., scoliosis) as wellas injuries may lead to structural instabilities, nerve or spinal corddamage, pain or other manifestations. Back pain (e.g., pain associatedwith the spinal column or mechanical back pain) may be caused bystructural defects, by injuries or over the course of time from theaging process. For example, back pain is frequently caused by repetitiveand/or high stress loads on or increased motion around certain boney orsoft tissue structures. The natural course of aging leads todegeneration of the disc, loss of disc height, and instability of thespine among other structural manifestations at or around the spine. Withdisc degeneration, the posterior elements of the spine bear increasedloads with disc height loss, and subsequently attempt to compensate withthe formation of osteophytes and thickening of various stabilizingspinal ligaments. The facet joints may develop pain due to arthriticchanges caused by increased loads. Furthermore, osteophytes in theneural foramina and thickening of spinal ligaments can lead to spinalstenosis, or impingement of nerve roots in the spinal canal or neuralforamina. Scoliosis may also create disproportionate loading on variouselements of the spine and may require correction, stabilization orfusion.

Pain caused by abnormal motion of the spine has long been treated byfixation of the motion segment. Spinal fusion is one way of stabilizingthe spine to reduce pain. In general, it is believed that anteriorinterbody or posterior fusion prevents movement between one or morejoints where pain is occurring from irritating motion. Fusion typicallyinvolves removal of the native disc, packing bone graft material intothe resulting intervertebral space, and anterior stabilization, e.g.,with intervertebral fusion cages or posterior stabilization, e.g.,supporting the spinal column with internal fixation devices such as rodsand screws. Internal fixation is typically an adjunct to attainintervertebral fusion. Many types of spine implants are available forperforming spinal fixation, including the Harrington hook and rod,pedicle screws and rods, interbody fusion cages, and sublaminar wires.

Spinal stenosis pain or from impingement of nerve roots in the neuralforamina has been treated by laminectomy and foraminotomy, and sometimesreinforced with rod and screw fixation of the posterior spine. Morerecently, surgeons have attempted to relieve spinal stenosis bydistracting adjacent spinous processes with a wedge implant. Pain due toinstability of the spine has also been treated with dynamicstabilization of the posterior spine, using elastic bands that connectpedicles of adjacent vertebrae.

The typical techniques for fusion, distraction, decompression, anddynamic stabilization require open surgical procedures with removal ofstabilizing muscles from the spinal column, leading to pain, blood loss,and prolonged recovery periods after surgery due in part to thedisruption of associated body structures or tissue during theprocedures.

To reduce the invasiveness of fusion procedures, some methods of fusionhave been proposed that do not require the extensive stripping ofmuscles away from the spinal column of earlier approaches. These involveposteriorly or laterally accessing the spine and creating spacesadjacent the spine for posterior stabilization. Some of these proceduresinclude fusion via small working channels, created with dilator typedevices or an external guide to create a trajectory channel between twoipsilateral neighboring pedicle screws. Also, placing support structuresbetween adjacent pedicle screws and across a joint requires accessingand working in an area from a difficult angle (the support structure istypically oriented somewhat perpendicular to an angle of access andthrough muscle and connective tissue). Furthermore, these stabilizationdevices typically involve the use of 4 pedicle screws (each having arisk associated with it when placed in the spine), two on each side of amotion segment, and are not ideally suited for percutaneousstabilization required across more than one or two segments.Accordingly, it would be desirable to provide a less invasive or lessdisruptive segmental spine stabilization procedure and implant that hasa reduced risk of damage or injury to associated tissue. It would alsobe desirable to provide an implanted posterior spine system that may beused to stabilize more than two motion segments in a less disruptive orless invasive manner.

One method of fusing a vertebra has been proposed using bilateral screwsthrough the lamina using a posterior approach. However, geometricplacement of the device is difficult and the procedure is considereddangerous because the laminar screws could enter through anteriorly intothe spinal canal and cause nerve damage.

Accordingly, it would be desirable to provide a device that reduces thedifficulties risks of the current procedures. It would also be desirableto provide a device that can be placed in a less disruptive or lessinvasive manner than commonly used procedures.

Unintended consequences of fixation include stress shielding of bone, aswell as transfer of load to adjacent, still dynamic motion segments, andeventual degeneration of adjacent motion segments. Flexiblestabilization of motion segments with plastic, rubber, super-elasticmetals, fabric, and other elastic materials has been proposed to providea degree of dynamic stabilization of some joints. Many of theseconstructs are not load bearing. Dynamic stabilization from pediclescrew to pedicle screw along the length of the spine has been proposed.However, this device has the disadvantage of requiring placement of 4pedicle screws and associated tissue disruption.

Due to the risks, inconvenience, and recovery time required for surgicalimplantation of spinal devices, some patients may continue to preferrigid fixation of a painful or degenerative motion segment over dynamicstabilization of the joint. In addition, doctors may be reluctant torecommend dynamic stabilization for patients with back pain, because itmay not alleviate pain to a patient's satisfaction.

Furthermore, even in patients who experience good relief of pain withdynamic stabilizers, it is anticipated that while the onset of arthriticchanges may be deferred, many patients will still eventually proceed todevelop degeneration, and require fixation of the motion segment toobtain pain relief. Repeat spine procedures to remove one implant andreplace it with another are associated with complications related tobleeding, surgical adhesions, destruction of bone, and other genericrisks associated with surgical procedures. Accordingly, improved devicesthat address these issues would be desirable.

A number of spinal deformities exist where the spine is abnormallytwisted and or curved. Scoliosis is typically considered an abnormallateral curvature of the vertebral column.

Correction of scoliosis has been attempted a number of ways. Typicallycorrection is followed by fusion. A Harrington rod has been used where acompressing or distracting rod is attached above and below a curved archof the deformity. The spine is stretched longitudinally to straightenthe spine as the rod is lengthened. The spine is then fused. Thecorrection force in this device and in similar devices is a distractionforce that may have several drawbacks including possible spinal corddamage, as well as the high loading on the upper and lower attachmentsites. Nowadays, segmental hook and screw fixation exists fordistraction and derotation corrective forces.

A Luque device has been used where the spine is wired to a rod atmultiple fixation points along the rod and pulls the spine to the rod.The spine is pulled to the rod with a wire and the spine is then fused.This does not provide significant adjustment over time and requiresfusion. Once completed this does not provide an opportunity for delayedadjustment over time. Anterior procedures also exist in the form offusion and newer technology involving staples across the disc space thatobviate the need for fusion but still correct the deformity. Thecorrective force is derotation with or without compression.

Accordingly it would be desirable to provide an improved correctivedevice for treating scoliosis or other deformities. It would also bedesirable to provide a device that may be used without fusion.

Spine surgeons commonly use metallic or polymeric implants to effect oraugment the biomechanics of the spine. The implants frequently areattached or anchored to bone of the spine. Sites typically consideredappropriate for boney attachment have high density or surface area, suchas, for example, the pedicle bone, the vertebral body or the corticalbone of the lamina. The spinous process contains thin walls of corticalbone, and thus, has been considered as not ideal for anchoring spinalimplants as they may not support the implants under physiologic loads,or the intermittent high loads seen in traumatic situations. Fixationhas been attempted from spinous process to spinous process with poorresults.

A translaminar facet screw as used by some surgeons goes through thebase of spinous process to access the cancellous bone of the lamina. Adisadvantage of this device is that it is not suitable for attaching toa pedicle screw and the depth and angle during deployment can be verydifficult to track or visualize, thus increasing the possibility thatthe screw would extend into the spinal canal. A facet screw is screwedbetween opposing facets of a zygapophyseal joint.

SUMMARY OF THE INVENTION

One aspect of the present invention is directed to providing a deviceand method for alleviating discomfort and or deformity associated withthe spinal column. Another aspect of the present invention is directedto providing a minimally invasive implant and method for alleviatingdiscomfort associated with the spinal column. Another aspect of thepresent invention provides an anchoring device and method that requiresless surrounding tissue damage or disruption. Another aspect of thepresent invention provides reinforcement of the spinous process for usein various spinal systems. Another aspect of the invention provides aminimally invasive, non-invasive, or remote adjustment or lengthening ofan orthopedic device. Another aspect of the invention provides aminimally invasive, non-invasive, or remote adjustment, lengthening orshortening of a stabilization device. Another aspect of the presentinvention also provides an implant system and device suitable forminimally invasive, minimally disruptive and/or percutaneous posteriordeployment across a plurality of motion segments and more than twomotion segments. Different aspects of the invention may providedistraction forces to relieve pressure on certain structures,compression forces to fix or stabilize motion across structures, shockabsorbing qualities to help relieve load from certain structures, andtherapeutic activity to reduce inflammation and pain. Other aspects ofthe invention may supplement or bear load for degenerated, painful, orsurgically removed joints, e.g., the facet joint. Another aspect of theinvention may provide a method and system for treating deformities suchas scoliosis. Other aspects of the invention may include sensorsassociated with implants or implanted at or near the bones, soft tissue,or joints of the spine and may provide feedback regarding the joint onan ongoing basis. The sensors may also be part of a feedback system thatalters a property of an implant in response to sensing information.Another aspect of the invention may provide a device or method fordelivering therapeutic substances at or near the spine.

In accordance with one aspect of the invention, a reinforcementstructure is provided for supporting the spinous process and if desired,in addition, the lamina of a spine. The invention further provides amethod and system for forming or implanting such structure in thespinous process or a region of cancellous bone in the lamina of a spine.The reinforcement system may include one or more systems ofreinforcement and may be used before, during and/or after a spinaldevice (e.g. a stabilization, distraction or prosthetic device, etc.) iscoupled to the spinous process.

Various aspects of the invention are set forth in the description and/orclaims herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a lateral posterior view of a vertebra with a reinforcementstructure in accordance with the invention.

FIG. 1B is a side view of the vertebra and reinforcement structure ofFIG. 1A.

FIG. 2A is a lateral posterior view of a vertebra with a reinforcementstructure in accordance with the invention.

FIG. 2B is a side view of the vertebra and reinforcement structure ofFIG. 2B.

FIG. 3A is a lateral posterior view of a vertebra with a reinforcementstructure in accordance with the invention.

FIG. 3B is a side view of the vertebra and reinforcement structure ofFIG. 3A.

FIG. 4A is a lateral posterior view of vertebrae with a reinforcementstructure and implant in accordance with the invention.

FIG. 4B is a side view of the reinforcement structure and implant ofFIG. 4A.

FIG. 4C is a top view of a reinforcement structure and implant inaccordance with the invention.

FIG. 4D is a posterior view of the reinforcement structure and implantof FIG. 4C.

FIG. 5 is a posterior view of a reinforcement structure and implant inaccordance with the invention.

FIG. 6 is a posterior view of a reinforcement structure and implant inaccordance with the invention

FIG. 7A is a top view of an implant implanted adjacent a motion segmentin accordance with the invention.

FIG. 7B is a posterior view of the implant as shown in FIG. 7A.

FIG. 8A is a top view of an implant implanted through the lamina and thezygapophyseal joint in accordance with the invention.

FIG. 8B is a posterior view of the implant as shown in FIG. 8A.

FIG. 9A is a top view of a dynamic implant in accordance with theinvention.

FIG. 9B is a posterior view of the implant as shown in FIG. 9A.

FIG. 10 is a schematic posterior portal cross sectional view of areinforcement device and implant in accordance with the invention.

FIG. 11 is schematic posterior partial cross sectional view of areinforcement device and implant in accordance with the invention.

FIG. 12A is an exploded perspective view of a reinforcement device andimplant in accordance with the invention.

FIG. 12B is a top view of the reinforcement device and implant of FIG.12A.

FIG. 13A is a schematic partial cross sectional view of an implant inaccordance with the invention in a first position.

FIG. 13B is a schematic partial cross sectional view of the implant ofFIG. 13A in a second, and implanted position.

FIG. 14A is a schematic partial cross sectional view of an implant inaccordance with the invention in a first position.

FIG. 14B is a schematic partial cross sectional view of the implant ofFIG. 14A in a second position.

FIG. 15 is a schematic side view of a connector of an implant inaccordance with the invention.

FIG. 16 is a schematic side view of a connector of an implant inaccordance with the invention.

FIG. 17 is a schematic perspective view of a connector in accordancewith the invention.

FIG. 18 is a schematic side perspective view of a dynamic element inaccordance with the invention.

FIG. 19 is a schematic side perspective view of an adjustable implantelement in accordance with the invention.

FIG. 20 is a schematic side perspective view of an adjustable implantelement in accordance with the invention.

FIG. 21 is a schematic side perspective view of an adjustable implantelement in accordance with the invention.

FIG. 22A is a schematic view of a spine deformity correction device inaccordance with the invention.

FIG. 22B is a cross section of FIG. 22A along the lines 22B-22B.

FIG. 22C is a schematic view of an adjustable pedicle attachment devicein a first position in accordance with the invention.

FIG. 22D is a schematic view of the adjustable pedicle attachment deviceof FIG. 22C in accordance with the invention.

FIG. 22E is a schematic side partial cross sectional view of analternative connector of the spine deformity device of FIG. 22A.

FIG. 22F is a schematic side partial cross-sectional view of analternative connector of the spine deformity device of FIG. 22A.

FIG. 22G is a schematic side partial cross sectional view of analternative connector of the spine deformity device of FIG. 22A.

FIG. 22H is a schematic side partial cross sectional view of analternative connector of the spine deformity device of FIG. 22A.

FIG. 23A is a schematic side view of a spine deformity correction devicein accordance with the invention.

FIG. 23B is a posterior view.

FIG. 24 is a schematic top view of an implant in accordance with theinvention.

FIG. 25 is a schematic posterior lateral perspective view of atherapeutic substance delivery device in accordance with the invention.

FIG. 26 is a schematic posterior lateral perspective view of atherapeutic substance delivery device in accordance with the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1A and 1B illustrate a reinforced posterior arch 100 of a firstvertebra 91 of a spine 90, including a spinous process 101 and lamina103. The first vertebra 100 of the spine 90 as illustrated includes afirst spinous process 101 with a superior portion 102 having a posteriorridge 104 into which a hole 105 is drilled. The hole 105 may be drilledwith a drill, a trocar, a large bore IV needle or similar sharp objectthrough the external and relatively hard cortical bone, to reach theinternal cancellous bone within the spinous process 101 and adjacent thelamina 103.

Once the cancellous bone is accessed, optionally, a tool such as aballoon tamp, or other expandable member or small crushing or drillingmember is used to create a cavity 107 or cavities within the cancellousbone by compressing, crushing or drilling out the bone material. X-raysmay be used to determine how far to drill into the bone. The cavity 107may be in the spinous process, through to the base of the spinousprocess, or through the spinous process and into the lamina. In oneembodiment the cavity is cone shaped or widens as it moves anteriorlytowards the lamina.

A reinforcing material is then delivered into the cancellous bone orcavity 107 of the spinous process 101 and/or within the lamina 103. Thematerial is selected to provide reinforcing properties to the spinousprocess 101 and/or lamina 103 sufficient to support (whether alone or incombination with other support elements) a spine support structure, aprosthesis, or other device attached to the spinous process and orsupported lamina. The material may be a bone cement or polymer withstrength and hardness properties selected to provide sufficientreinforcement to the region so that the spinous process may be used atleast in part, to support an implant structure for attaching to andmanipulating the biomechanics of the spine. Examples include but are notlimited to polymers such as acrylic cement developed for use invertebroplasty procedures. The material may be a flowable polymermaterial that cures within the cavity. Suitable materials may be readilyselected by one of ordinary skill in the art.

Reinforcement structures may be placed within the cavity prior to,during or after injection of flowable material for further strengthproperties. As illustrated, an additional support structure 106 isprovided within the cavity. The support structure 106 may be insertedthrough a cannula and released to expand as a spring-like orself-expanding member, into the cavity. The support structure 106provides further support of the spinous process and/or lamina.Alternatively, or additionally, one or more posts or struts may beprovided within the cavity or extending out of the spinous process orlamina from the area of cancellous bone, to supplement the support ofthe spinous process or lamina in combination with the polymer or othercurable material. The reinforcement structures may be formed of a numberof different materials such as, e.g., a metal or biocompatible polymer.Such reinforcement structures may also be used in other bony areas ofthe spine including the vertebra, the pedicles, facets, the transverseprocess, etc.

As shown in FIGS. 2A and 2B, an inferior portion 109 of a spinousprocess 108 may also be reinforced. Similarly a hole 110 is drilled inthe inferior portion of the spinous process 108 and a cavity 111 isformed. The cavity 111 is similarly filled with a curable polymer and isreinforced by reinforcing elements 112 positioned within the cavity.

The reinforcement structure may be used in a number of applicationsincluding increasing the strength of healthy bone to support the loadand fixation of orthopedic implants, as well as increasing the strengthof bone weakened by osteoporosis, chronic steroid use, avascularnecrosis, weakened by injury and cancer involving the bone. According toone aspect, the reinforcement structure comprises a material thatprovides sufficient strength including but not limited to suitablepolymers, e.g. PEAK, titanium, steel and carbon fiber.

The stabilizing and/or distracting devices described herein may beformed of a material that provides sufficient column strength includingbut not limited to suitable polymers, e.g. PEAK, titanium, steel, andcarbon fiber.

Referring to FIGS. 3A and 3B, an alternative support structure 120 isillustrated. The support structure 120 allows the anchoring of implantsunder physiologic loads on the spinous process 101 while shieldingunderlying bone from loads that would normally cause the bone tofracture. (The implants may alternatively or in addition be anchored orattached to the lamina 103, e.g., with addition of small screws, barbsor adhesive that engage with the lamina while avoiding injuring thespinal cord surrounded by the lamina.) The support structure 120comprises a hood like element positioned over the posterior arch 100,i.e., the spinous process 101 and lamina 103 of a spine 90. The supportstructure 120 may be made of a moldable or malleable material (e.g.putty, formable ceramic, clay-like material, or a moldable polymer ormalleable alloy or metal) that cures into or forms a solid, strongstructure. Heat, light, catalysts, precursors, or local pressure andforce, for example, may be used to make the hood moldable or firm. Thesupport structure of filling material to support the spinous process maybe constructed or formed of moldable composites that can cure into hardmaterial such as, e.g., ground glass powder or glass fiber fillers mixedinto an acrylic matrix and activated with light or other biophysicalmodalities. Other cements or other curable materials may be suitable aswell. The support structure 120 further comprises openings 121 to guidedrill bits and/or for the placement of screws, reinforcement posts, orother instruments or supplemental support structures. The guide mayinsure accurate positioning of the implant. The support structure 120may be anchored on the posterior arch by mold bending or forming thestructure about the anatomy. The support structure 120 may be anchoredinto the lamina or spinous process by anchoring elements, such as, e.g.,screws or barbs. The support structure 120 may also be anchored viascrews or posts. Alternatively, the support structure 120 could be apreformed implant with contours that fit the anatomy of the posteriorarch 100 or that are malleable or moldable to the anatomy. Also, thesupport structure 20 may be anchored into the pedicles 122 with screws,into the underlying bone with barbs, screws, bone anchors, or adhesives,over the edges of structures with hooks, or may be constructed of aplurality of pieces that may be assembled into one piece around thebone. Wings 120 a of support structure may be placed over the lamina tospread the force of any device attached to the support structure 120.

As illustrated in FIGS. 3A and 3B, a sensor 120 b is positioned on thesupport structure 120. The sensor 120 b may be embedded in the material.The sensor may sense stress on the support structure 120 from implantssecured to it, or may sense other information that may be desirable tomonitor. The sensor may include a communication element configured tocommunicate sensed information to an external device, e.g., wheninterrogated.

Referring to FIGS. 4A-4D, a support structure 130 is illustratedpositioned over a posterior portion 132 of a spinous process 131 withwings 130 a over the lamina 103 including small screws 130 b into lamina103. Wings 130 a may help spread the force from any devices attached orcoupled to the support structure 130. Pedicle screws 135 are anchoredinto pedicles 136 and are further anchored into the spinous process 131through screws 134 positioned through holes 133 in the support structure130. As shown in FIG. 4C, the screw 134 includes a sensor 134 a that maybe used to sense loads on the device. Use of such sensors is describedfurther herein. The pedicle screw 135 includes a screw capture device135 a for receiving a screw or rod of a spinous process screw or otherrod. The capture device 135 a may be a polyaxial head of a pedicle screwit may include a hole, a threaded screw hole with a washer or cap. Crossbar 135 b is positioned across the spine between heads of pedicle screws135 to prevent pedical screws from creeping laterally. A wedge shapednut 134 d between the head 134 c of the screw 134 and the supportstructure. Another nut 134 b may be positioned between support structure120 and pedicle screw, and secure against the support structure 120.These features may be used in a similar manner in the embodimentsdescribed herein.

FIG. 5 illustrates the spinous process screws 134 coupled to a spinousprocess 101 of a first vertebra 91 through a hood or support structure130 in a manner similar to that described above with respect to FIGS.4A-4D. The screws 134 extend bilaterally across the posterior of asecond vertebra 92 and are anchored to capture elements 135 a of pediclescrews 135 anchored into pedicles 93 a of a third vertebra 93.

FIG. 6 illustrates a device for stabilizing or distracting the spinewith pedicle screws 135 and cross bar 135 b positioned as in FIG. 4D.Hood structure 132 includes openings for receiving screws 132 b coupledto the hood 132 on one end and to the heads 135 a of pedicle screws 135and on the other end. The screws 132 b do not penetrate the spinousprocess. Obliquely threaded nuts secure the screws 132 b against thehood 132.

The reinforcement or supporting devices described herein may be used inconjunction with a number of different spine devices, including, forexample, the various distraction, fusing or dynamic stabilizing devicesdescribed herein. The hoods or reinforcement devices herein may also becustomized, for example by using stereolithography. The hoods orreinforcement devices may be used for example with a brace. The pediclescrew may be telescoping as described with respect to FIGS. 22C and 22D.

The devices described herein may be coupled to the spinous process usingminimally invasive techniques. These techniques may includepercutaneously accessing the spinous process and/or using dilators toaccess the spinous process at an oblique angle with respect to medianplane m and/or horizontal plane h through the spine of the patient.

FIG. 7A is a side view of a joint of the spine with a fixation devicepercutaneously implanted to fuse adjacent vertebrae by fixation of thefacet joints. Pedicle screw 146 in the pedicle 143 of the adjacentvertebral members 141, 142. As illustrated in FIG. 7B, the pedicle screw146 has a polyaxial screw head 147 for receiving a spinous process screw148 having a tapered tip. The spinous process screw 148 is screwed fromthe contralateral side of the spinous process, through the spinousprocess 140 of vertebral member 141, adjacent the facet joint 149between the vertebral member 141 and vertebral member 142, and thencaptured or placed into the head 147 of the pedicle screw 146.

When implanted, the pedicle screws are positioned in the pedicles in agenerally known manner. The facet joint or facet joints between thespinal members that are to be fused, are debrided and grafted. A flankstab wound is made to expose the base of the spinous process. Thespinous process screw is then inserted and navigated through the woundto the spinous process and/or soft tissue. Tissue dilators or retractorsmay be used to facilitate insertion of the spinous process screw throughsoft tissue. The spinous process screw 148 is then placed through thespinous process 140, and into and captured by the head 147 of thepedicle screw 146. Compression across and the facet joint 149 may beprovided using a nut placed in the polyaxial head of the pedicle screw.Alternatively, external compression may be used prior to placement ofthe oblique rod of the spinous process screw. A similar screw may alsobe placed from the spinous process 140 to the contralateral pedicle. Thespinous process 140 may be reinforced prior to or after placing thescrew 148.

Referring to FIG. 8A, a similar fusion system as illustrated withrespect to FIGS. 7A and 7B. Pedicle screw 156 is positioned in thepedicle 153 of the adjacent vertebral members 151, 152. The pediclescrew 156 has a polyaxial screw head 157 for receiving a spinous processscrew 158 having a tapered tip. The spinous process screw 158 is screwedfrom the contralateral side of the spinous process 150, through thespinous process 150 of vertebral member 151, through the facet joint 159between the vertebral member 151 and vertebral member 152 and then intothe head 157 of the pedicle screw 156.

An oblique skin stab wound is made to navigate to the base of thespinous process 150, which may be exposed under direct vision. Thespinous process screw 158 (or other device) is then placed through thespinous process 150, across (adjacent or through) the facet joint 159,and into the head 157 of the pedicle screw 156 (or otherwise attached toa pedicle attachment device for attaching devices to the pedicle),immobilizing the facet joint 159. A similar screw may also be placedfrom the spinous process 150 to the contralateral pedicle. The spinousprocess may be reinforced prior to or after placing the screw or otherdevice. The other devices attached or coupled to the spinous process asdescribed herein may be similarly deployed.

The devices described herein may be coupled to the spinous process usingminimally invasive techniques. These techniques may includepercutaneously accessing the spinous process and/or using dilators toaccess the spinous process at an oblique angle with respect to medianplane and/or horizontal plane through the spine of the patient.

Referring to FIGS. 9A and 9B, a spine is illustrated with a spinalfusion system in place. A spinous process screw 168 is placed from thecontralateral side of the spinous process 160, through the spinousprocess 160 of a first vertebra 161 and across the facet joint 169between the first vertebra 161 and an adjacent second vertebra 162, andinto the pedicle 164 of the second vertebra 162.

Another feature of the spinous process screw of FIGS. 9A-9B is that itmay be configured to exert flexible, stabilizing, nonfusion forces tothe motion segment. For example, this may be used in the event thatpatient suffers from pain due to laxity or other dysfunction of thespinal structures (e.g. degenerative spondylolisthesis). In other words,the looseness or other dysfunction of the joint and surrounding tissuemay cause pain. The present invention provides a device and method fordynamically stabilizing (or reducing) such a joint while allowing someflexibility and movement. The device and method provide suchstabilization on an oblique angle with respect to the rotational axis ofthe spine, i.e. at an oblique angle with respect to the median andhorizontal planes of the spine. The spinous process and a pedicle couldalso be used to anchor a device exerting a stabilizing or compression orcontractile force between the two anchors on an oblique angle. Devicesthat may be used to exert such a contractile force may include, forexample, polymeric materials, super elastic metals, and fabrics. Thespinous process screw 168 includes a sensor 165 a that may be used tosense motion of the distraction device. The forces or stresses on thedevice may be monitored and used to determine if it is necessary toconvert the device to a fusion type device or to otherwise reduce oralter motion. The sensor may also be used as a diagnostic device tomeasure the amount of joint motion upon insertion of the implant or overtime.

The system illustrated in FIGS. 9A and 9B may also be used for thetreatment of spondylolysis, to attain stability across the parsinterarticularis.

The spinous processes 140, 150, 160 may be reinforced in a manner asdescribed herein. The various rods or screws through the spinousprocesses 140, 150, 160 may also be positioned through a posterior archreinforcing member as described herein.

FIG. 10 illustrates a spinous process rod or screw 60 in accordance withthe invention. The spinous process rod or screw 60 comprises an elongateportion 61 configured to extend through the reinforcement hood 51 (forexample, as described in further detail herein with reference to FIGS.3A-4D positioned around spinous process 50 and into an adjacent elementsuch as, e.g. a pedicle screw. The spinous process rod or screw 60 mayinclude threaded portions. The distal end 62 of the rod may be threadedor otherwise configured to engage an adjacent element. The spinousprocess screw or rod 60 further comprises a proximal securing element 65located on the proximal portion 64 of the spinous process screw or rod60. The proximal securing element 65 is configured to engage a firstwall 52 portion of the spinous process 60 or reinforcement hood 51.(“Engage” as used herein means to either directly or indirectly engage.)As illustrated, the distal securing element 63 comprises an obliquelythreaded nut that is configured to receive screw 61 which is coupled tothe hood 51 at an oblique angle with respect to the wall 53. The obliquethreaded nut may be used in other applications where a screw is obliquewith respect to the object to which is engaged, coupled or attached. Theobliquely threaded nut may have a predetermined angle at which itdirects the screw with respect to the hood to guide the desired angle ordirections of the screw placement. This may be predetermined based onimaging of a particular patient's anatomy. A distal securing element 63is provided more distal of the proximal securing element 65. The distalsecuring element is configured to engage a second wall portion 53generally opposite the first wall portion 52 so that the spinous processelement is secured or fixed to the hood and spinous process. (The term“fix” as used herein means either directly or indirectly fix to and mayinclude dynamic elements.)

FIG. 11 illustrates a spinous process rod or screw 80 in accordance withthe invention. The spinous process rod or screw 80 comprises an elongateportion 81 configured to extend through the reinforcement hood 71 (forexample, as described in further detail herein with reference to FIGS.3A-4D) positioned around spinous process 70 and into an adjacent elementsuch as, e.g. a pedicle screw. The spinous process rod or screw 80 mayinclude threaded portions. The distal end 82 of the rod may be threadedor otherwise configured to engage an adjacent element, e.g. with aconnecting member, including but not limited to connecting membersdescribed herein. The spinous process screw or rod 80 further comprisesa proximal securing element 85 located on the proximal portion 84 of thespinous process screw or rod 80. The proximal securing element 85 isconfigured to engage a first wall 72 portion of the spinous process 70or reinforcement hood 71. (“Engage” as is used herein to mean eitherdirectly or indirectly engage.) A hollow space or chamber 74 is formedin the reinforcement hood 71 so that the hollow chamber may engageablyreceive one or more securing elements, e.g. first and second securingelements 86, 87 therein. The securing elements 86, 87 may be positionedon either or both sides of the spinous process 70 through which thescrew or rod 80 is positioned. As illustrated in FIG. 11, securingelement 86 is positioned on the proximal portion 84 of the screw 80while securing portion 87 is positioned on the distal portion 82 of thescrew 80. Securing elements 86, 87 may be obliquely threaded nuts, forexample, as described with respect to nut 80 b in FIG. 3E. Securingelements may be attached a variety of ways, for example as illustratedin FIGS. 12A-12B and 13A-13B. FIGS. 12A-12B illustrate manual insertionof securing elements in accordance with the invention. Spinous processscrew 80 a is placed through both wings of the hood 71 while passingthrough holes 1000 as shown. Securing elements 86 a and 87 a areinserted into receiving holes 1001 within the hood 71 and receivingholes 1002 within the spinous process screw 80 a. Securing elements 86a, 87 a prevent movement of the spinous process screw 80 a. FIGS.13A-13B illustrate automatic deployment of securing elements inaccordance with the invention. The securing elements 86 b and 87 b couldbe positioned in recesses 1004 in the spinous process screw 80 b andspring loaded with springs 1003 attached inside of the recesses 1004. Anexternal sheath 1005 is positioned around the spinous process screw 80b. The screw 80 b is positioned through a spinous process and a hood.The securing elements are then deployed upon removal of an externalsheath 1005. The securing element 86,86 a, or 86 b is configured toengage the first wall portion of the spinous process (or hood) fromwithin the hood 71. The securing element 87, 87 a, or 87 b is configuredto engage a second wall portion 73 generally opposite the first wallportion 72 so that the spinous process element is secured to the hoodand spinous process.

FIGS. 14A and 14B illustrate a spinous process rod or screw 54 inaccordance with the invention. The spinous process rod or screw 54comprises an elongate outer tube portion 55 and an inner rod portion 56.The inner rod portion 56 is configured to move longitudinally within thetube portion 55 to lengthen or shorten the spinous process screw or rod54. The inner wall of the tube portion 55 may include a threaded innerwall that mates with a threaded outer wall of the rod 54 so that the rodmay be screwed to advance the rod 56 and thereby lengthen or shorten thespinous process screw or rod 54. Once the outer rod 55 and screw 56 arepositioned within a spinous process or hood 51 the spinous process screwor rod 54 may then be lengthened as shown in FIG. 14B to extend throughthe reinforcement hood 51. The lengthened spinous process screw may beused to distract the spinal segment or segments as well.

The pedicle attachment devices herein may include a sensor that may beused to sensor one or more parameters e.g., strain, pressure, motion,position change, that provides information about possible screw failure.The sensor may communicate the information to an external device, e.g.telemetrically, and may be passively powered by an external device.

According to another aspect of the invention a rod is provided that isanchored to with pedicle screws with screw heads made of or attached toswivel collars, polyaxial heads, or other movable fasteners to allow fornear physiologic levels of motion of the spinal motion segment. Angularmovement may be provided where a distracting element attaches on eitherside of a motion segment so that when distracting or lengthening thedevice, there is accommodation in the device for the change of anglethat occurs.

FIG. 15 illustrates an enlarged portion of a spinal prosthesis. Theprosthesis 280 may provide support of the load on the spine where afacet has been removed or may provide other support or distraction. Theprosthesis 280 comprises a distraction bar 281 used to distract a motionsegment of the spine in a number of manners including the distractiondevices described herein. A pedicle screw 283 is screwed into a pedicleof the spine or other anatomical location. The distraction bar 281includes and articulating cup 282 having an inner surface 282 a. Thepedicle screw 283 has a ball 284 received by and coupled to the cup 282of the distraction bar 281. In addition to shock absorbing capabilitiesdescribed in various embodiments herein, the distraction bar 281 alsoarticulates with a portion of the spine to which the pedicle screw 283is attached.

FIG. 16 illustrates a variation of the prosthesis 280 described withrespect to FIG. 15. The prosthesis 285 comprises a distraction bar 286and an articulating ball 287 configured to engage and couple with anarticulation cup 289 of a pedicle screw 288. The prosthesis 285 operatesin a similar manner as prosthesis 280.

FIG. 17 illustrates a variation of the prostheses 280, 285 describedherein respectively with respect to FIGS. 15 and 16. The prosthesis 290comprises a distraction bar 291 having an end 292 with a lumen 293 forslidably receiving the end 296 of a pedicle screw 295. The end 296 ofthe pedicle screw 295 comprises a ball portion 297 attached to a neck298. The ball 297 portion is configured to slide within the lumen 293 ofthe distraction bar 291 which contains the ball portion 297. The neck298 of the pedicle screw 295 extends out of the distraction bar 291through a longitudinal slit 294 that slidably receives the narrower neckportion 298 of the pedicle screw 295.

One embodiment of the invention is a rod anchored at each end across amotion segment that can be “switched” between dynamic stabilization andrigid fixation in a minimally invasive, percutaneous, or non-invasivefashion. One way for this to occur is injection of a flowable materialwithin the lumen of the device, which would cure, and immobilize thecomponents which allow for motion. Electrical current, heat, mechanicalenergy, or other techniques could also be used to render movablecomponents fixed. Another method is insertion of a rigid implant axiallyalong the length of the dynamic implant. This method of rendering aflexible prosthesis rigid may be applied to the design of othercombination motion/fixation prostheses, including disc, facet hip, knee,fingers shoulder, elbows, and ankle prostheses, etc.

FIGS. 18-21 illustrate convertible or adjustable dynamic stabilizationdevices for joints. The stiffness or flexibility of the device may bealtered or titrated after implantation to adapt the stiffness to aparticular patient, and/or to adjust the stiffness over time, forexample when laxity of the joint increases with age. Referring to FIG.18 illustrates a dynamic stabilization prosthesis 350. The prosthesiscomprises a flexible coil 352 contained in a tube member 351 comprisingtelescoping tubes. The prosthesis 350 may be used in a number of mannersaffixed across a joint motion segment to dynamically stabilize thejoint. The coil 352 may be energy absorbing. The coil 352 may also beconfigured to exert a distracting force on the joint when implanted.FIG. 19 illustrates the dynamic stabilization prosthesis 350 of FIG. 18converted to a rigid or more rigid prosthesis. The prosthesis 350includes a slit 353 for receiving a rigid wire member 354. In FIG. 19the rigid wire member 354 is inserted into the slit 353 to form theprosthesis from a dynamic prosthesis into a rigid prosthesis. As analternative to a rigid wire member, a flexible coil of a selectedstiffness may be inserted to change the stiffness of the dynamicprosthesis. The tube may alternatively comprise a ferromagnetic materialcontained therein and an electromagnetic field is applied that causesthe prosthesis to become stiffer. The field may be varied to provide avariety of gradients in stiffness. The device may also include a sensorthat operates as sensor 170 a described herein. Feedback may be providedand the stiffness of the prosthesis adjusted accordingly. The stiffnessmay be varied when implanted using patient feedback so that the implantis more or less flexible depending upon an individual patient's needs.In addition the stiffness may be changed at different times during thecourse of the implants lifetime. For example, the stiffness may beincreased when an increased amount of stabilization is required.

FIG. 20 illustrates an alternative prosthesis 360 also comprising aflexible coil 362 contained in a tube member 361. The tube member isconfigured to receive a fluid material such as a curable polymer 364that cures in the tubular member to create a rigid prosthesis. Asillustrated in FIG. 20 a rigid prosthesis is formed from a dynamicprosthesis by injecting the polymer material 364 into the tubular member361. The flexibility/stiffness properties of the prosthesis may beselected by selecting such properties of the polymer to be injected.

As illustrated in FIG. 21 a flexible prosthesis 365 is illustrated. Theflexibility of the prosthesis 365 is adjustable by injecting a polymermaterial into one or more of the columnar cavities 367, 368, 369. Thepolymer may be injected into each cavity at a different time so thestiffness of the prosthesis may be increased gradually over time. Thestiffness/flexibility properties of the polymer injected may also beselected according to a desired stiffness/flexibility of the implant.

According to an embodiment of the invention, the dynamic stabilizer maycomprise a shock absorber that has both energy absorbing and energydissipating properties. The tension band effect of the posterior columnsmay also offload the pressures borne by anterior column of the spine. Soin addition to helping to protect the facet joints, other aspects of theinvention would help slow the progression of degenerative disc disease,annular degradation, disc herniation, and vertebral compressionfractures.

Another aspect of the invention is to supplement implants or repairprocedures of the anterior column with a posterior shock absorber device(rod, screw, plate). Examples of these implants or procedures includetotal disc replacements, annular repair, artificial nucleus, andvertebroplasty/kyphoplasty.

Another aspect of the invention is to supplement implants or repairprocedures of the posterior column with a shock absorber rod. Examplesof these implants or procedures include interspinous distraction wedges,facet joint replacements, and posterior arch replacements.

Another aspect of the invention provides a posterior support implantswith shock absorbing properties, to decrease or remove the loadexperienced by the facets. Implant components may include springs,coils, hydraulic or fluid filled piston chambers, or elastic materials.Each end of the device could be anchored in such a fashion so the rodbridges the facet joint, reducing the loads borne by the joint. This isbelieved to reduce wear of the facets and resulting pain and alteredspinal biomechanics

An improved device is provided that utilizes the spinous process, thepedicle, adjacent ribs and/or a transverse process or a combinationincluding one or more of these anatomical structures, to correct orstabilize a deformed spine. The device may be used to correct scoliosisusing one or more of these anatomical structures and multiple points ata plurality of spine segments. The correction may be made incrementallyover time and may or may not include a fusion process.

In one embodiment, a percutaneously and obliquely placed rigid ordynamic stabilizer is provided. Stabilizer segments are anchored to baseof spinous process at one end and a pedicle screw at the other end, as aunilateral temporary stabilizer. The dynamic stabilizers describedherein may be adjusted over time to gradually bring the spine inalignment. The stabilizer may be used to derotate (untorque) and correctthe spine. A stabilizer placed across a motion segment, i.e., not at thesame vertebral level may be used to create overgrowth where desired,i.e. on the non-instrumented side of the motion segment. Such overgrowthmay help stabilization or correction of the spine.

FIGS. 22A-24 illustrate an explantable, temporary scoliosisstabilization device. The system is configured to be manipulable once itis installed. The systems illustrated are configured to alter theorientation of a vertebral body and in particular to untorque the spineabout the axis of the spinal column as well as applying a correctivestraightening or translation force with respect to a vertical rod.According to one aspect of the invention, a device for correctingdeformities of the spine is provided where the device may be adjustedover time to direct the corrective forces as needed over time. Accordingto another aspect, a multipoint stabilizing device is coupled to theposterior portions of the spine.

The systems illustrated in FIGS. 22A-24 comprise a multipoint anchoringmechanism that provides for multidimensional correction of the spinal orspinal segments by positioning the anchor at a plurality of locations ona spine. As illustrated for example in FIGS. 22A-22H, the multiplelocations include the spinous process and pedicle of a particularvertebra. A bar is attached between the spinous process and pedicle. Aforce directing device couples the bar to a vertical rod. As illustratedin FIGS. 23A-23B, the multiple locations include the spinous process ofone level and the pedicle of another level (e.g. an adjacent level). Asillustrated in FIG. 24, the multiple locations include the spinousprocess, through a transverse process 605 into a costal aspect of a rib606. The vertical rod in these figures is attached or coupled to thespine at neutral and balanced vertebra, typically only at the most upperand most lower positions.

The device comprises a telescoping rod (or plate) 536 to which varioussegments of the spinal column are to be fixed. The rod 536 telescopes toadjust the height to accommodate particular segments or a height of thespine. As illustrated in FIG. 22A a portion 500 of the spine comprises aplurality of adjacent segments 501, 502, 503, 504, 505, (additionaladjacent segments may also be corrected). The portion 500 of the spineexhibits a concave curvature between segments 501 and 505. Pediclescrews 506, 507, 508, 509, 510 are attached to pedicles of segments 501,502, 503, 504, 505, respectively. Dynamic stabilizers 516, 517, 518,519, 520 are attached to pedicle screws 506, 507, 508, 509, 510 and tospinous processes 521, 522, 523, 524, 525 respectively of segments 501,502, 503, 504, 505. Wires 526, 527, 528, 529, 530 attached to the rod536 via hooks 531, 532, 533, 534, 535 attached to the rod 536. The wires526, 527, 528, 529, 530 are used to tension the portion of the spine 500to pull on the concavity. If the portion has a convexity, rods may beused in place of wires to push on the convexity to straighten the spine.

FIG. 22B is a cross section of FIG. 22A along the lines 22B-22B. Thepedicle screw 508 includes a screw capture device 508 a for receiving ascrew head or rod of a dynamic stabilizer, in this case, a spinousprocess screw 518. The capture device may be a hole, a threaded screwhole with a washer or cap. The pedicle screw 508 may be configured totelescope outwards or inwards to be positioned to receive the screw heador rod of a dynamic stabilizer 518 as shown in FIGS. 22C and 22D. Thespinous process screw 518 is shown in 22C where, given the trajectory ofthe spinous process screw 518, its end does not intercept the capturedevice 508 a of the pedicle screw 508. As shown in FIG. 22D the pediclescrew's trunk 508 b is lengthened with a telescoping or other similarlengthening mechanism so that the end of the spinous process screw 518may be positioned in the capture device 508 a.

The spinous process screw 518 is anchored through the reinforced spinousprocess 523 (having a reinforcement hood 523 a or is otherwisereinforced as described herein. Note that the reinforcement hood mayhave a single lamina wing where a single screw is attached as opposed tobilateral screws) with a head portion 518 a engaging the pedicle screw508 and a rod portion 518 b extending through a reinforced spinousprocess 523. The dynamic stabilizer 518 includes a loop connector end518 c for receiving a hook 518 d of a wire (or a telescoping rod) 528that is attached to the rod 536 with a ratcheted connector 533. The wiremay also be a rod, spring, elastic band or other force-directing device.The loop connector end 518 c may also be a poly axial connector thatallows translation in a variety of directions or places, i.e., so thatan oblique angle rod can be captured. (for example, similar to pediclescrew 508 and capture device 508 a) The wire 528 may be adjusted ortightened at various times with the ratcheted connector 533, e.g.,during a period of time where the spine is being corrected. As the spineis straightened, excess wire may be trimmed off. This procedure may bedone percutaneously, e.g. by accessing wire near the skin. Each dynamicstabilizer is similarly constructed.

FIGS. 22E-22H illustrate various dynamic stabilizers that may be used tocorrect spinal deformity. Dynamic stabilizers 518 e, 518 i, and 518 mare coupled by coupling mechanisms 541 a-c to the telescoping rod 536.The coupling mechanisms 541 a-c may be positioned on or through theplate or telescoping rod 536. Dynamic stabilizer 518 e includes rod 518f that will extend through a reinforced spinous process and is coupledby a coupling mechanism 518 g to rod 518 h in an end-to-end fashion. Rod518 h slidably extends through opening in coupling mechanism 541 aattached to the telescoping rod 536. The rod 518 h is adjustable withinthe coupling mechanism 541 a to lengthen or shorten the distance of thedynamic stabilizer 518 e between the spinous process and the telescopingrod 536. The coupling mechanism 541 a is configured to clamp down on therod 518 h to secure it in place once the distance has been adjusted. Thecoupling mechanisms 541 a-c may include a screw, cam or clamp mechanismto clamp or lockably engage rods 518 h, 1, and p as described in useherein.

Similarly, dynamic stabilizer 518 i includes rod 518 j that will extendthrough a reinforced spinous process and is coupled by a couplingmechanism 518 k to rod 5181 in an end to side fashion. Rod 5181 slidablyextends through opening in coupling mechanism 541 b attached to thetelescoping rod 536. The rod 5181 is adjustable within the couplingmechanism 541 b to lengthen or shorten the distance of the dynamicstabilizer 518 i between the spinous process and the telescoping rod536. The coupling mechanism 541 b is configured to clamp down on the rod5181 to secure it in place once the distance has been adjusted.

Dynamic stabilizer 518 m includes a rod 518 n that will extend through areinforced spinous process and is coupled by a threaded coupling 518 oto rod 518 p. The rod 518 p is slidably and rotatably positioned withina cylindrical hole in coupling mechanism 541 c attached to thetelescoping rod 536. The rod 518 p may be rotated, i.e., screwed orunscrewed so that the stabilizer lengthens or shortens at the threadedcoupling 5180. The rotation or screwing may be actuated at or near theskin where the rod 518 p is positioned in the coupling mechanism 541 c.

Dynamic stabilizer 518 q includes a rod 518 r that will extend through areinforced spinous process and is coupled by a multiaxial coupling 518 ssimilar to a multiaxial screw head type coupling, to rod 518 t. The rod518 t is a telescoping rod and is coupled by coupling mechani8sm 541 dto the vertical rod 536.

Each of the dynamic stabilizers may include sensors located thereon tosense data corresponding to a parameter of the dynamic stabilizationdevice or the spine. FIG. 22E-22H illustrate sensors 542 a-542 d locatedon the dynamic stabilizer. The sensors may comprise, e.g., a strain,stress, pressure, position or motion sensor. Such sensors may include avariety of sensors that are generally know. For example, strain gauges,accelerometers or piezo electric sensors may be employed to senseparameters that correspond, e.g., to the position of the spine, avertebra, a dynamic stabilizer, as well as the parameters relating tothe forces or mechanical loads that are effecting the device. Each ofthe sensors may individually sense information or information relativeto each of the other sensors may be sensed and compared. The informationmay be used to set tension on the device, to identify when repositioningis necessary or to otherwise provide information as to the status of thedevice or portions thereof, or status of the spine that is beingtreated. The sensors may include some level or circuitry including, e.g.a telemetry circuit that transmits information concerning the sensors toan external device. The sensors may be battery powered or may usepassive circuits that are powered by an external device. The informationmay be used to identify when one of the stabilizers no longer hastension associated with the stabilizer thus identifying when the tensionneeds to be modified in the device. Accordingly, each segment may bemoved separately, monitored separately and adjusted separately form theother segments. Each segment may be moved to a different degree and indifferent directions or at different angles with varying forces.

FIG. 23A illustrates an alternative configuration of the correctiondevice according to the invention. A portion 550 of the spine comprisesa plurality of adjacent segments 551, 552, 553, 554, 555, 555 a(additional adjacent segments may also be corrected). The portion 550 ofthe spine exhibits a concave curvature between segments 551 and 555 a.Pedicle screws 556, 557, 558, 559, 560 are attached to pedicles ofsegments 551, 552, 553, 554, 555, respectively. Dynamic stabilizers 566,567, 568, 569, 570 are attached to pedicle screws 556, 557, 558, 559,560 and through spinous processes, 572, 573, 574, 575, 576 respectivelyof adjacent segments 555 a, 551, 552, 553, 554. Thus, the dynamicstabilizers are positioned across the motion segments between thecorresponding adjacent segments. The dynamic stabilizers 566, 567, 568,569,570 attached to the telescoping rod 576 in one or more manners suchas, for example, the dynamic stabilizers 518, 518 e, 518 i, 518 m, 518 qas illustrated in FIGS. 22A-22H, herein. The dynamic stabilizers 566,567, 568, 569, 570 are used to tension the portion of the spine 500 topull on the concavity, or if the portion has a convexity, to push, pullon, or translate the convexity to straighten the spine. Thus each of thedynamic stabilizers are attached a plurality of locations on the spineand operate to stabilize adjacent segments with respect to each other.

FIG. 23B illustrates a pedicle screw and dynamic stabilizer in greaterdetail. The pedicle screw 558 is screwed into pedicle 563 of vertebra553. The pedicle screw 558 includes a screw hole 558 a for receiving ascrew head or rod of a dynamic stabilizer 568. A screw capture device568 b such as a nut or a threaded portion of the pedicle screw isconfigured to capture and receive the dynamic stabilizer screw or rodportion 568 a. The capture device 568 b of the stabilizer engages thepedicle screw 558 and a rod portion 568 b extends through a reinforcedspinous process 574. The dynamic stabilizer 568 includes a connector end580 for receiving a wire 578 or a hook of a telescoping rod that isattached to the telescoping rod 576. The dynamic stabilizer 568 isanchored through the reinforced spinous process 574 of an adjacentvertebra 554 (FIG. 17A) thus immobilizing or stabilizing the motionsegment between the vertebra 553, 554. This device may also be used infusion, i.e. to fuse the motion segments across vertebra of a multipointconnector. The device may also be used to encourage overgrowth atcertain locations. In particular it may encourage overgrowth on thenon-fused lateral side of a vertebra (opposing the fused lateral side)stabilized with the multipoint connector between two vertebrae.

FIG. 24 illustrates a device for treating a deformity such as scoliosis.The device includes a dynamic stabilizer 600 comprising a spinousprocess screw 601 and a pedicle screw 602 including a spinous processscrew capture device 603. The spinous process screw is configured to bepositioned through a reinforced spinous process 604 and through atransverse process 605 into a costal aspect of a rib 606. The dynamicstabilizer 600 includes a connector portion 607 configured to beconnected to a telescoping rod as described herein with reference toFIGS. 22A-H and 23A-23B. Similar to FIGS. 22A-H and 23A-23B, a pluralityof segments may be secured to a telescoping rod with a plurality ofdynamic stabilizers. The pedicle screw in this and all other embodimentsdescribed in this application may include a telescoping portion that canadjust the length of the screw head from the anchoring point where thepedicle screw is anchored into the bone. The pedicle screw 602 alsoincludes a sensor 608 located thereon (or incorporated therewith). Thesensor may comprise, for example, a motion detector, a positiondetector, a pressure sensor, a strain gauge, and ultrasonictransducer/sensor. The sensor may sense a change in strain on the screwthat may be due to loosening or repositioning of the screw. The sensormay also sense a change in position of the screw that indicates a changein alignment and corresponding loosening or repositioning of the screw.The sensor may also sense a change in pressure due to loosening orrepositioning of the screw. The sensor may also include an ultrasonictransducer and transmitter that can determine change in positioning ofthe screw, e.g. loosening of the screw indicated by a change ininterfaces of materials or characteristic property change indicatingscrew loosening or repositioning. The sensor may include someelectronics such as a telemetry circuit that allows it to communicatewith an external device. The sensor may also be powered by an externaldevice e.g., in a manner generally known in the art.

The various embodiments of the invention described herein may includesensors integrated with or provided on a structural spinal implant. Anumber of factors may be detected as described herein. Additionalfactors may include, e.g., local inflammation, pressure, tension, edema,motion, water content, and electrolytes or other chemicals. The sensorsallow a doctor to monitor patients for response to healing, or may beused by the doctor to guide serial adjustments to the patient'streatment. For example, measurements from the sensing means could leadthe doctor to change the length or tension of a distraction rod orstabilization device. Patients could adjust therapy based onmeasurements from the sensing device, or could be alerted to notifytheir doctor should certain measurements be of concern. The sensor isconfigured to be adjustable to sensed stresses. The sensor may forexample, be a strain gauge, a pressure sensor accelerometer, positionsensor, imaging device, etc. The sensor may be used in the initialadjustment of the prosthesis or may be monitored over time. The sensormay sense shear/torsion tension/compression. Sensors may sense stressesat various motion segments. The sensor may be used to compare stressesat various motion segments or locations. Various sensors may be selectedfrom sensors that are known to one of skill in the art or that arecommercially available.

Anchoring of Therapeutic Devices

Some patients obtain back pain relief with injections of steroids andanesthetic agents at the site of pain; however the relief is temporaryrequiring that patients return for repeat injections when their painrecurs.

One embodiment of the invention comprises an anchor device with atherapeutic substance or drug delivery device, e.g. a drug port and/orreservoir, or matrix attached to a vertebra. In one embodiment, thedevice is anchored adjacent a site near where pain is present. The portis configured to deliver steroids or anesthetic agents via a catheter toa desired location, for example, the facet joint, neural foramen,vertebral body, annulus, nucleus, back muscles, back ligaments, bonemetastases, intrathecal space, epidural space, or other targets in, on,or around the spine. The catheter can direct the drug to the correctlocation by positioning the end of the catheter at a target location.The port is configured to be refilled periodically percutaneously, e.g.using an imaging device and a percutaneously placed needle that caninject the refill into the port, e.g. through a biocompatible polymer orrubber type port access mechanism. The device further comprises apatient actuation mechanism for patient control of drug delivery asneeded for pain relief, manually or remotely using a telemetricallytriggered delivery from an external telemetry control device. Accordingone aspect of the invention such a device is attached to a boneystructure of the spine. Other device that may be attached to the spinemay include sensory or therapeutic devices, including nerve stimulators,bone growth stimulators and radioactive seeds.

In addition, a structural implant could be anchored to bone, to which asensory or therapeutic device could be attached. The sensory ortherapeutic device could be placed external to the bone, on the surfaceof the bone, or internal to the bone.

FIGS. 25 and 26 illustrate drug delivery devices 370, 380, respectively,in accordance with the invention. The drug delivery device 370 includesa reservoir 375 attached by an anchor 371 configured to anchor thereservoir 375 to the bone of the spine. In particular, in thisembodiment, the anchor 371 comprises a pedicle screw that anchors thedevice to the pedicle 373 of a vertebra 372. The reservoir 375 includesa catheter 376 in communication with the contents of the reservoir 375and having an end positioned adjacent or in a zygapophyseal joint 378where the drug is directed to have a therapeutic effect on the joint378. The device may include a telemetrically actuable pump mechanism fordelivering the drug to the joint upon telemetric actuation by anexternal control device. The device 370 further comprises a port 377 forreceiving (e.g. via a percutaneously introduced needle) into thereservoir 375, refills of the therapeutic substance or drug. Device 380comprises a similar catheter 386, and reservoir 385 attached by ananchor 381 to the spinous process 383 or alternatively an adjacentlamina 384. The spinous process 383 or lamina 384 may be reinforcedprior to attachment of the anchor 381 or may be attached to areinforcement device positioned at the posterior arch of the spine, asdescribed herein with reference to FIGS. 1A-7B.

1. A spinal implant for stabilizing vertebrae of a spine, comprising: afirst connector configured to be coupled to a spinous process of a firstvertebra, the first connector including one or more plates shaped togenerally conform to the curvature of a surface of a spinous process,and a penetrating structure for penetrating the spinous process, whereinthe first connector comprises a single plate that is shaped to wraparound a spinous process from a first side to a second side thereof,wherein the single plate has a first aperture on a first side thereofand a second aperture on a second side thereof, wherein the first andsecond apertures are aligned; a second connector spaced apart from thefirst connector a sufficient distance to allow it to be coupled to apedicle of a second vertebra that is adjacent to or next adjacent to thefirst vertebra, the second connector being located at an oblique angleto the first connector, and including a pedicle-penetrating structuresuitable for attaching the second connector to a pedicle of a spine; anda first generally rod-shaped member extending at an oblique angle fromthe first connector to the second connector and interconnecting thefirst connector and the second connector to limit relative motiontherebetween, the first generally rod-shaped member extending into thefirst aperture and out of the second aperture, wherein the length of thefirst generally rod-shaped member between the first and secondconnectors is adjustable after the implant is implanted.
 2. The spinalimplant of claim 1 wherein the length of the first generally rod-shapedmember varies in response to applied force, and the first generallyrod-shaped member comprises at least one cavity, and wherein the extentof variation in the length of the first generally rod-shaped member isadjustable to change the amount of said movement by inserting a materialin said cavity.
 3. The spinal implant of claim 2 wherein the firstgenerally rod-shaped member is adjustable to change the amount of saidmovement by inserting a curable polymer in said cavity.
 4. A spinalimplant for stabilizing vertebrae of a spine, comprising: a firstconnector configured to be coupled to a spinous process of a firstvertebra, the first connector including one or more plates shaped togenerally conform to the curvature of a surface of a spinous process,and a penetrating structure for penetrating the spinous process, whereinthe first connector comprises a single plate that is shaped to wraparound a spinous process from a first side to a second side thereof, andthe single plate includes a first aperture on a first side thereof and asecond aperture on a second side thereof; a second connector spacedapart from the first connector a sufficient distance to allow it to becoupled to a pedicle of a second vertebra that is adjacent to or nextadjacent to the first vertebra, the second connector being located at anoblique angle to the first connector, and including apedicle-penetrating structure suitable for attaching the secondconnector to a pedicle of a spine; a first generally rod-shaped memberextending at an oblique angle from the first connector to the secondconnector and interconnecting the first connector and the secondconnector to limit relative motion therebetween, wherein the length ofthe first generally rod-shaped member between the first and secondconnectors is adjustable after the implant is implanted; a thirdconnector spaced apart from the first connector by about the samedistance as is the second connector, the third connector being locatedat an oblique angle to the first connector, and including apedicle-penetrating structure suitable for attaching the third connectorto a pedicle of a spine; and a second generally rod-shaped memberextending at an oblique angle between the first connector and the thirdconnector and interconnecting the first connector and the thirdconnector to limit relative motion therebetween, wherein the firstgenerally rod-shaped member extends into the first aperture and out ofthe second aperture, and the second generally rod-shaped member extendsinto the second aperture and out of the first aperture.
 5. The spinalimplant of claim 4, wherein the third connector is spaced laterallyapart from the second connector such that the pedicle-penetratingportions of the second and third connectors can respectively penetratedifferent pedicles of the same vertebra.
 6. The spinal implant of claim4, wherein the first and second generally rod-shaped members can eachvary in length in response to an externally applied force, sufficient toprovide shock absorbing properties and permit some relative movementbetween the first connector, on the one hand, and the second and thirdconnectors, on the other hand.
 7. The spinal implant of claim 6, whereinthe first and second generally rod-shaped members can each vary inlength due to incorporation of a compressible member therein.
 8. Thespinal implant of claim 7, wherein the compressible member is a spring.9. The spinal implant of claim 7, wherein the compressible member is aresilient polymer.